Production of dibenzanthrone



Patented Feb. 16, 1932 UNITED STATES I LLOYD c. DANIELS, on GRAFTON, JPENNSYLVANTA, ASSIGNOR TQ THE SELDEN GOM-.

PATENT oFF-ice PANY, OF PITTSBURGH, PENNSYLVANIA, A CORPQR-ATION OF DELAWARE PRODUCTION OF DIBENZANTHRONE No Drawing.

dextrin, and isodibenzanthrone has been pro duced by fusions of 'chlorbenzonthrone in alcoholic caustlc potasha The fusion proc-' esses for producing dibenzanthrone and 1sodibenzanthrone have been open to a number s of serious disadvantages. In the first. place the amount of caustic potash requiredin the fusions is very high, amounting normally to from ten to twelve times the theoretical amount required to react. The large excess.

has been necessary in order to produce a satisfactorily fluid melt. isodibenzanthrone fusion a large excess of alkali over that theoretically required has also been necessary because of the low boiling point of alcohol which necessitated alarge excess in order to maintain sufficient alcohol in the liquid state in the melt. The excess alcohol has to be recovered and this recovery is not complete. The prior precessesfor making dibenzanthrone also produced large amounts of impurities, the normal yield of dye being not more than 50% based on'the benzanthrone used, which not only means a loss of benzanthrone but also increases the cost of transforming dibenzanthrone into the nitrocompound in which form it is usually sold. 7

According to the present invention dibenzanthrone fusions are carried out in the presence of heterocyclic carbonyl compounds in which are included aldehydes, alcohols, ketones, etc. Liquid carbonyl compounds C011,", taining the furane or hydrogenated furane nucleus, such as furfural and its homologues, furfuryl alcohol, liquid condensation products of furfural and acetone, or methyl ethyl ketone, etc., constitute the preferred class under the present invention, furfural being particularly effective in the dibenzanthrone fusion. c

When the reducing agents of the present invention are used a much smaller amount is In the caseof the.

Application filed. April 4, 1929; ,Serial No. 352,805.

generally sufiicient, the amount of caustic potash can be greatly decreased, particularly with the preferred liquid reducing agents, and the products obtained show higher percentages of dyethan is obtainable in the prior processes. The improvement is especially marked in the diben zanthrone fusion.

using furfural. Since the chief costs in the a process are the caustic potash and benzane throne, the reduction in the amounts of both of these ingredients, and especially the marked reduction possible in the amount of caustic potash when using the preferred liquid solvents of the. present invention, rep- 1 resent very great savings, which savings are still further increased when the dibenzanthrone products are to be used for the pro: duction of nitrodibenzanthrone as in this case in additionto the lower cost of the di benzanthrone compound further savings in reagents, especially nitrating'mixture and hydrosulfite used in reduclng the crude nitroproduct, are effected byreasonofthe-greatly decreased percentage of non-vatable impurities produced in crude dibenzanthrone product. i a A The following Specific examples give a few typical embodiments of the present invention with some of the preferred class of solvents, but the lnventlon 1s in nosense restricted to the details therein set forth, andparticularly to obtain only'the advantages of higher purity of product. Such processes are, ofcourse, lncluded 1n the present lllVBIltlOll as well as those in which the advantages of improved yieldare combined with a'reduction in the amount of caustic potash used and which processes represent usuallythe greatest saving and. constitute the preferred, embodiments of the invention. The parts are parts by weight.

' Example 1 q r 100 parts benzanthrone are ground With 5 parts of furfural and added slowly at 220 1W C. to a mixture of 300 parts of 90% caustic potash and 2% parts of furfural. After the addition of the benzanthrone the mixture is heated to 240 C. for 45 minutes, after which the dibenzanthrone is isolated by pouring the melt into water, oxidizing the leuco-compound with air and filtering in the usual The product obtained is of superior quality giving brighter and stronger dyeings and the yield is better than when carbohydrates are used in the standard fusion and a notable saving is eflected; by reason of the fact that only threefifths as much caustic potash is used as that ordinarily required. The amount of furfural may vary and where an extremely fluid melt is desired the amount of furfural may be doubled.

300 parts of 90% caustic potash and from 2% to 5 parts of furfuryl alcohol. After adding the benzanthrone the mixture is heated to complete thefusion, as described in Example 1, an excellent dibenzanthrone compound being obtained.

Example 5 100 parts of chlorbenzanthrone are fused in'a mixture containing 300 parts of 8590% KOH and 120 parts of furfural. If desired, part of the furfural may be mixed with the ichlorbenzanthrone and added to the caustic potash and the remainder of the furfural. The fusion is carried out under a refiuxcondenser at the ordinary temperatures used in alcoholic fushions of chlorbenzanthrone.

-.Excellent yields of isodibenzanthrone are obtained and as the furfural is consumed and it is unnecessary to use an'excess no recovery costs are entailed as is the case when alcohol is used as a reducing agent and flux. The

amount of caustic potash is only about threefifths that normally requiredand represents a very notable saving.

What is claimed as new is:

1. A method of fusing a benzanthronecom- .IPOIlIlCl to produce a dibenzanthrone compound, which comprises fusing a benzanthrone compound wth caustic alkali in the presence of a liquid carbonyl compound containing the furane nucleus.

pound to produce a dibenzanthrone com- 7 pound, which comprises fusing the benzanthrone compound with caustic alkali in the presence of furfural.

4. A method according to claim 3, in which the amount of caustic potash used does not exceed three parts to one of the benzanthrone compound.

5. A method of fusing benzanthrone to produce dibenzanthrone, which comprises fusing the benzanthrone with caustic alkali in the presence of a liquid carbonyl .compound containing a. furane nucleus.

6. A method according to claim 5, in which the amount of caustic potash used does not exceed three parts to one of the benzanthrone.

7. A method of fusing benzanthrone to produce dibenzanthrone, which comprises fusing the benzanthrone with caustic alkali in the presence of furfural.

8. A method according to claim 7, in which the amount of caustic potash used does not exceed three parts to one of the benzanthrone compound.

9. A method of preparingisodibenzanthrone, which comprises fusing a halogenated benzanthrone with caustic potash in the presence of a liquid carbonyl compound containing the furane nucleus.

'10. method according to claim 9, in which the amount of caustic potash is not more than three parts to one of halogenated benzanthrone.

11. A method of preparing isodibenzanthrone, which comprises fusing a halogenated benzanthrone with caustic potash in the presence of furfural.

12. A method according to claim 11, in which the amount of caustic potash is not more than three parts to one of halogenated benzanthrone.

Signed at Pittsburgh, Pennsylvania, this 29th day of March, 1929.

LLOYD C. DANIELS.

J; 2. A method according to claim 1, in which 

